1. Field of the Invention
The present invention relates to a zoom lens system for use in a photographic lens of a camera or the like.
2. Description of the Related Art
As a conventional zoom lens system having a wide-angle position where a half-angle-of-view is in general more than about 30.degree., a simple two-lens-group zoom lens system, which is composed of a negative lens group (the first lens group) and a positive lens group (the second lens group) in this order from the object, has been used. In particular, the zoom lens systems which are disclosed in Japanese Unexamined Publication No. 60-55311 and Japanese Unexamined Publication No. 4-114115 have mainly been developed for the purpose of cost-reduction. However, both of these zoom lens systems have employed a lens material having a high refractive index to form a negative lens element in the first lens group. It is known that lens materials having a high refractive index are in general expensive since various kinds of ingredients are mixed to attain high refractive index. The production cost of zoom lens systems has not yet been sufficiently reduced in the prior art.